1. Field of the Invention
The present invention is concerned with improved energy transmission devices such as fluid-mechanical and mechanical-fluid motors, pumps and certain actuators, meters and couplers. More particularly and in one preferred aspect of the invention, energy translation devices of the type disclosed in U.S. Pat. No. 3,796,525 are described, which are improved by provision of an individually compensated valving arrangement, fluid displacement piston assemblies having enhanced sealing properties, and a counterbalancing mechanism which produces a centrifugal force equal to, but in the opposite direction, to the centrifugal force generated by the orbiter member of the unit. In view of the foregoing, U.S. Pat. No. 3,796,525 is incorporated by reference herein.
2. Description of the Prior Art
In its particular aspects, the present invention pertains to devices of the general class which employ a pair of relatively rotatable machine elements in combination with an intermediate orbital member coupled therebetween. Such devices assume a variety of forms, such as those described in the following patents: U.S. Pat. Nos. 3,215,043, 3,391,608, 3,490,383, 3,516,765, 448,607, 3,613,510, 2,989,951, 3,443,378, 2,423,507 and 3,796,525, French Patent No. 980,766, Swiss Patent No. 202,323 and German Patent No. 392,327.
Although units of the above type have achieved widespread usage, certain problems remain. For example, in one type of known device, the orbiting member carries a plurality of spaced apart piston and cylinder assemblies, and the orbiter is slotted adjacent each assembly for purposes of delivery and return of hydraulic fluid to the piston assemblies. These slots, due to the orbital motion of the member, are alternately connected to pressure and exhaust slots in the main frame. In addition, the orbiter in this device floats laterally between a frame and back plate. Accordingly, the spaced apart valving slot in the gear must be relatively wide to present a large effective area and accommodate the movement of the orbiter. This in turn results in the generation of relatively high hydraulic forces (particularly during high pressure operations) which serve to push the backplate away from the frame, and results in increased clearance between the frame and orbiting member. This can cause excessive leakage at the region of the valving slots. It is to be understood in this respect that a certain minor amount of leakage at these areas is required for good lubrication; however, excessive leakage lowers the efficiency of the device. Therefore, the problem has been to design for proper fluid leakage which is substantially constant and largely independent of operational pressure.
Another problem heretofore present in certain orbiter devices stems from undue friction and wear of the piston and cylinder assemblies, and the general complexity of these assemblies. That is to say, the piston and cylinder units are necessarily subjected to varying pressures during operation, and it has therefore been difficult to properly seal the same against excessive fluid leakage while at the same time avoiding large mechanical loadings and consequent undue friction and wear at the sealing areas. Thus, the designer has heretofore been faced with a seemingly irreconcilable dilemma between proper sealing and extreme wear, and has been forced to make undesirable design compromises.
Finally, in any device utilizing an oribiting member there is inherently a mechanical imbalance, which under dynamic conditions produces a mechanical vibration. This vibration results from centrifugal forces which are proportional to the weight of the orbiting member multiplied by the radius of the orbit (which is in turn equal to the eccentricity of the orbiter's path). This vibration can be undesirable, especially in large devices and at higher operational speeds.